diff --git a/.gitignore b/.gitignore
index 5504786..759e66d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1041,4 +1041,5 @@ dkms.conf
 
 # VKAPI
 include/Config.hpp
+include/nlohmann*
 src/main.cpp
\ No newline at end of file
diff --git a/.gitmodules b/.gitmodules
index e69de29..6d12152 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "submodules/json"]
+	path = submodules/json
+	url = https://github.com/nlohmann/json
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f8c61b5..0db77ac 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,26 +7,28 @@ include(GNUInstallDirs)
 
 set(VKAPI_MAJOR_VERSION 0)
 set(VKAPI_MINOR_VERSION 0)
-set(VKAPI_PATCH_VERSION 5)
+set(VKAPI_PATCH_VERSION 8)
 set(VKAPI_VERSION_STRING "${VKAPI_MAJOR_VERSION}.${VKAPI_MINOR_VERSION}.${VKAPI_PATCH_VERSION}")
 
-configure_file(${CMAKE_CURRENT_SOURCE_DIR}/include/Config.hpp.in ${CMAKE_CURRENT_SOURCE_DIR}/include/Config.hpp @ONLY)
-
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
 if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
     set(MACOSX TRUE)
 endif()
 
-set(NLOHMANN_JSON_PATH "${PROJECT_SOURCE_DIR}/include")
+# set(NLOHMANN_JSON_PATH "${PROJECT_SOURCE_DIR}/include")
 set(CMAKE_INSTALL_PREFIX ${CMAKE_SOURCE_DIR})
 
 option(BUILD_LIBRARY "Determines that, as a result, we get" ON)
 option(BUILD_EXAMPLES "Determines whether examples should be performed" ON)
 
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/include/Config.hpp.in ${CMAKE_CURRENT_SOURCE_DIR}/include/Config.hpp @ONLY)
+
 file(GLOB TARGET_SRC "./src/*.cpp")
 file(GLOB TARGET_HEADERS "./include/*.hpp")
 
+include(submodules/install.cmake)
+
 if(BUILD_LIBRARY)
     add_library(${PROJECT_NAME} STATIC ${TARGET_SRC} ${TARGET_HEADERS})
 else()
@@ -37,10 +39,11 @@ else()
     add_executable(${PROJECT_NAME} ${TARGET_SRC} ${TARGET_HEADERS})
 endif()
 
+# Include headers
 target_include_directories(${PROJECT_NAME} PUBLIC ${CMAKE_INSTALL_INCLUDEDIR})
 
-# Include json
-target_link_directories(${PROJECT_NAME} PUBLIC ${NLOHMANN_JSON_PATH})
+# Link nlohmann_json
+target_link_libraries(${PROJECT_NAME} PUBLIC nlohmann_json)
 
 # Link curl
 if(UNIX)
@@ -48,7 +51,6 @@ if(UNIX)
     target_link_directories(${PROJECT_NAME} PUBLIC ${CURL_INCLUDE_DIR})
 else()
     include(FindPkgConfig)
-    # find_package(CURL REQUIRED)
     pkg_check_modules(CURL libcurl REQUIRED)
 endif()
 
diff --git a/VKAPIConfig.cmake.in b/VKAPIConfig.cmake.in
index 80ee4b0..9699401 100644
--- a/VKAPIConfig.cmake.in
+++ b/VKAPIConfig.cmake.in
@@ -1,4 +1,5 @@
 include(CMakeFindDependencyMacro)
+
 find_dependency(CURL REQUIRED)
 
 @PACKAGE_INIT@
diff --git a/examples/1/main.cpp b/examples/1/main.cpp
index 957e205..853337f 100644
--- a/examples/1/main.cpp
+++ b/examples/1/main.cpp
@@ -15,7 +15,7 @@ int main(int argc, const char** argv)
         } else {
             std::cout << "Auth is failed!" << std::endl;
         }
-    } catch (std::exception ex) {
+    } catch (std::exception& ex) {
         std::cout << ex.what() << std::endl;
     }
 
diff --git a/examples/2/main.cpp b/examples/2/main.cpp
index d0c8388..631f8c3 100644
--- a/examples/2/main.cpp
+++ b/examples/2/main.cpp
@@ -23,7 +23,7 @@ int main(int argc, const char** argv)
         } else {
             // The further behaviour
         }
-    } catch (std::exception ex) {
+    } catch (std::exception& ex) {
         std::cout << ex.what() << std::endl;
     }
 
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index da7a51a..4b93793 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -3,7 +3,7 @@ project(VKAPI_TESTS LANGUAGES CXX)
 
 set(VKAPI_MAJOR_VERSION 0)
 set(VKAPI_MINOR_VERSION 0)
-set(VKAPI_PATCH_VERSION 5)
+set(VKAPI_PATCH_VERSION 8)
 
 set(MODULES 1 2)
 
diff --git a/include/BotBase.hpp b/include/BotBase.hpp
index c3fbba3..b19fab3 100644
--- a/include/BotBase.hpp
+++ b/include/BotBase.hpp
@@ -2,7 +2,7 @@
  * Contains the class for working with vkbot.
  * @file BotBase.hpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
 #ifndef VKAPI_BOTBASE_HPP
@@ -19,7 +19,7 @@ namespace base
 namespace bot
 {
 
-constexpr const char* DEFAULT_TIME_WAIT = "25";
+_VKAPI_CONSTEXPR const char* DEFAULT_TIME_WAIT = "25";
 
 /**
  * @brief The class for working from bots by Long Poll Server.
@@ -160,7 +160,6 @@ class BotBase : public ClientBase
      *
      * @retval a string (URL) of this method.
      */
-    _VKAPI_COMPLEXITY_FUNCTION
     _VKAPI_STATIC std::string MethodToString(METHODS method);
 
     /**
@@ -226,7 +225,6 @@ class BotBase : public ClientBase
      *
      * @retval the type of event in enum (EVENTS).
      */
-    _VKAPI_COMPLEXITY_FUNCTION
     _VKAPI_STATIC EVENTS GetTypeEvent(const std::string& typeEvent);
 
 private:
@@ -269,6 +267,8 @@ class BotBase : public ClientBase
     std::string m_timeStamp;
 
     std::string m_timeWait;
+
+    
 };
 
 } // namespace bot
diff --git a/include/ClientBase.hpp b/include/ClientBase.hpp
index f37dfd7..69dcb69 100644
--- a/include/ClientBase.hpp
+++ b/include/ClientBase.hpp
@@ -2,7 +2,7 @@
  * Contains general objects for working with VK API.
  * @file ClientBase.hpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
 #ifndef VKAPI_CLIENTBASE_HPP
@@ -14,6 +14,7 @@
 #include "Utilities.hpp" // ConvertStrToUrlCode
 #include "Exceptions.hpp" // already_connected, not_connected, empty_argument
 #include "Defines.hpp"
+#include "Types.hpp"
 
 #ifdef __VKAPI_VERSION_ADDED_OPTIONAL
 #if __VKAPI_COMPILED_VERSION >= __VKAPI_VERSION_ADDED_OPTIONAL
@@ -39,22 +40,14 @@ namespace vk
 namespace base
 {
 
-#ifndef VKAPI_OPTIONAL_HPP
-typedef nlohmann::json JsonType;
-
-typedef long long int IdType;
-typedef unsigned long long UIdType;
-typedef bool IndicatorType;
-#endif // VKAPI_OPTIONAL_HPP
-
 #define VKAPI_INVALID_REQUEST "invalid_request"
 #define VKAPI_NEED_CAPTCHA "need_captcha"
 
-constexpr const char* VKAPI_API_URL = "https://api.vk.com/method/";
-constexpr const char* VKAPI_AUTH_URL = "https://oauth.vk.com/token?";
-constexpr const char* VKAPI_OAUTH_URL = "https://oauth.vk.com/authorize?";
-constexpr const char* VKAPI_OAUTH_URL_SECOND = "https://oauth.vk.com/access_token?";
-constexpr const char* VKAPI_API_VERSION = "5.120";
+_VKAPI_CONSTEXPR const char* VKAPI_API_URL = "https://api.vk.com/method/";
+_VKAPI_CONSTEXPR const char* VKAPI_AUTH_URL = "https://oauth.vk.com/token?";
+_VKAPI_CONSTEXPR const char* VKAPI_OAUTH_URL = "https://oauth.vk.com/authorize?";
+_VKAPI_CONSTEXPR const char* VKAPI_OAUTH_URL_SECOND = "https://oauth.vk.com/access_token?";
+_VKAPI_CONSTEXPR const char* VKAPI_API_VERSION = "5.120";
 
 // The types of error which the VK server can return.
 // You can see the description of these on https://vk.com/dev/errors
diff --git a/include/Defines.hpp b/include/Defines.hpp
index cf5f02a..3e14d55 100644
--- a/include/Defines.hpp
+++ b/include/Defines.hpp
@@ -2,7 +2,7 @@
  * Contains general defines about the language.
  * @file Defines.hpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
 #ifndef VKAPI_DEFINES_HPP
@@ -35,65 +35,37 @@
 #endif // (__cplusplus >= 202002L)
 
 #ifdef __CPLUSPLUS_OVER_11
-#ifndef _VKAPI_OVERRIDE
-#define _VKAPI_OVERRIDE override
-#endif // _VKAPI_OVERRIDE
+#define _VKAPI_OVERRIDE     override
+#define _VKAPI_FINAL        final
+#define _VKAPI_NOEXCEPT     noexcept
+#define _VKAPI_EXPLICIT     explicit
+#define _VKAPI_CONSTEXPR    constexpr
 
-#ifndef _VKAPI_FINAL
-#define _VKAPI_FINAL final
-#endif // _VKAPI_FINAL
-
-#ifndef _VKAPI_NOEXCEPT
-#define _VKAPI_NOEXCEPT noexcept
-#endif // _VKAPI_NOEXCEPT
-
-#ifndef _VKAPI_EXPLICIT
-#define _VKAPI_EXPLICIT explicit
-#endif // _VKAPI_EXPLICIT
-
-#ifndef _VKAPI_MOVE
 #include <utility>
-#define _VKAPI_MOVE(x) std::move(x)
-#endif // _VKAPI_MOVE(x)
+#define _VKAPI_MOVE(x)      std::move(x)
 #else
-#ifndef _VKAPI_OVERRIDE
 #define _VKAPI_OVERRIDE
-#endif // _VKAPI_OVERRIDE
-
-#ifndef _VKAPI_FINAL
 #define _VKAPI_FINAL
-#endif // _VKAPI_FINAL
-
-#ifndef _VKAPI_NOEXCEPT
 #define _VKAPI_NOEXCEPT
-#endif // _VKAPI_NOEXCEPT
-
-#ifndef _VKAPI_EXPLICIT
 #define _VKAPI_EXPLICIT
-#endif // _VKAPI_EXPLICIT
-
-#ifndef _VKAPI_MOVE
-#define _VKAPI_MOVE(x) x
-#endif // _VKAPI_MOVE
+#define _VKAPI_CONSTEXPR
+#define _VKAPI_MOVE(x)      x
 #endif
 
-#ifndef _VKAPI_VIRTUAL
-#define _VKAPI_VIRTUAL virtual
-#endif // _VKAPI_VIRTUAL
+#define _VKAPI_VIRTUAL      virtual
+#define _VKAPI_INLINE       inline
 
-#ifndef _VKAPI_INLINE
-#define _VKAPI_INLINE inline
-#endif // _VKAPI_INLINE
-
-#ifndef _VKAPI_UNUSED
 #define _VKAPI_UNUSED(x) (void)(x)
-#endif // _VKAPI_UNUSED
 
 #if defined(_MSC_VER)
+#define _VKAPI_MSVC 1
+
 #define __DISABLE_WARNING_PUSH           __pragma(warning(push))
 #define __DISABLE_WARNING_POP            __pragma(warning(pop))
 #define __DISABLE_WARNING(warningNumber) __pragma(warning(disable : warningNumber))
 #elif defined(__GNUC__) || defined(__clang__)
+#define _VKAPI_CLANG 1
+
 #define __DO_PRAGMA(X)                   _Pragma(#X)
 #define __DISABLE_WARNING_PUSH           __DO_PRAGMA("GCC diagnostic push")
 #define __DISABLE_WARNING_POP            __DO_PRAGMA("GCC diagnostic pop")
@@ -104,11 +76,32 @@
 #define __DISABLE_WARNING
 #endif
 
+#ifndef _VKAPI_MSVC
+#define _VKAPI_MSVC 0
+#endif // _VKAPI_MSVC
+
+#ifndef _VKAPI_CLANG
+#define _VKAPI_CLANG 0
+#endif // _VKAPI_CLANG
+
+#if _VKAPI_MSVC
+#define _VKAPI_UNUSED_FOR_ANALYZER
+#elif _VKAPI_CLANG
+#define _VKAPI_UNUSED_FOR_ANALYZER __attribute__((unused))
+#endif
+
+#ifndef _VKAPI_DEBUG_PRINT
+#if __DEBUG__
+#define _VKAPI_DEBUG_STDCERR(x) (std::cerr << (x))
+#define _VKAPI_DEBUG_STDCOUT(x) (std::cout << (x))
+#else
+#define _VKAPI_DEBUG_STDCERR(x)
+#define _VKAPI_DEBUG_STDCOUT(x)
+#endif // __DEBUG__
+#endif // _VKAPI_DEBUG_PRINT
+
 #ifndef __VKAPI_VERSION_ADDED_OPTIONAL
 #define __VKAPI_VERSION_ADDED_OPTIONAL __VKAPI_VERSION_NUM(0, 0, 7)
 #endif // __VKAPI_VERSION_ADDED_OPTIONAL
 
-// TODO(#14): Write defines for disable complexity warnings
-#define _VKAPI_COMPLEXITY_FUNCTION
-
 #endif //VKAPI_DEFINES_HPP
diff --git a/include/Exceptions.hpp b/include/Exceptions.hpp
index 75b6a62..0aa6cb6 100644
--- a/include/Exceptions.hpp
+++ b/include/Exceptions.hpp
@@ -2,9 +2,11 @@
  * Contains exceptions and information about them of this library.
  * @file Exceptions.hpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
+// TODO (#17): Add comments about exceptions
+
 #ifndef VKAPI_EXCEPTIONS_HPP
 #define VKAPI_EXCEPTIONS_HPP
 
@@ -40,7 +42,7 @@ class BaseException : _VKAPI_VIRTUAL public std::exception
 class AlreadyConnectedException : _VKAPI_VIRTUAL public BaseException
 {
 public:
-    explicit AlreadyConnectedException()
+    _VKAPI_EXPLICIT AlreadyConnectedException()
         : BaseException("The client is already connected to Long Poll Server!")
     {}
 };
@@ -48,7 +50,7 @@ class AlreadyConnectedException : _VKAPI_VIRTUAL public BaseException
 class NotConnectedException : _VKAPI_VIRTUAL public BaseException
 {
 public:
-    explicit NotConnectedException()
+    _VKAPI_EXPLICIT NotConnectedException()
         : BaseException("The client is not already connected to Long Poll Server!")
     {}
 };
@@ -56,7 +58,7 @@ class NotConnectedException : _VKAPI_VIRTUAL public BaseException
 class EmptyArgumentException : _VKAPI_VIRTUAL public BaseException
 {
 public:
-    explicit EmptyArgumentException()
+    _VKAPI_EXPLICIT EmptyArgumentException()
         : BaseException("The size of argument's symbols cannot equal zero!")
     {}
 };
@@ -64,11 +66,19 @@ class EmptyArgumentException : _VKAPI_VIRTUAL public BaseException
 class RequestError : _VKAPI_VIRTUAL public BaseException
 {
 public:
-    explicit RequestError()
+    _VKAPI_EXPLICIT RequestError()
         : BaseException("Request returned unknown errors!")
     {}
 };
 
+class AuthFailed : _VKAPI_VIRTUAL public BaseException
+{
+public:
+    _VKAPI_EXPLICIT AuthFailed()
+        : BaseException("Authorization completed with an error!")
+    {}
+};
+
 } // namespace ex
 
 } // namespace vk
diff --git a/include/Optional.hpp b/include/Optional.hpp
index b49d51d..32b63fa 100644
--- a/include/Optional.hpp
+++ b/include/Optional.hpp
@@ -2,7 +2,7 @@
  * Describes optional class.
  * @file Optional.hpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
 #ifndef VKAPI_OPTIONAL_HPP
@@ -11,6 +11,8 @@
 #include <vector>
 
 #include "Defines.hpp"
+#include "Types.hpp"
+
 #include "nlohmann/json.hpp"
 
 namespace vk
@@ -56,7 +58,7 @@ class BasicOptional
         m_isSet = true;
     }
 
-    const _Type& Get() const& _VKAPI_NOEXCEPT
+    _VKAPI_INLINE const _Type& Get() const& _VKAPI_NOEXCEPT
     { return m_val; }
 
     void Clear()
@@ -94,12 +96,6 @@ class Optional : public BasicOptional<T>
 
 #endif // defined(__CPLUSPLUS_OVER_17)
 
-typedef long long int IdType;
-typedef unsigned long long UIdType;
-typedef bool IndicatorType;
-
-typedef nlohmann::json JsonType;
-
 typedef Optional<IdType> Opt_IdType;
 typedef Optional<UIdType> Opt_UIdType;
 typedef Optional<const std::string&> Opt_StrType;
diff --git a/include/Request.hpp b/include/Request.hpp
index cf40a7f..dbc100f 100644
--- a/include/Request.hpp
+++ b/include/Request.hpp
@@ -2,7 +2,7 @@
  * Describes the class for working with CURL.
  * @file Request.hpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
 #ifndef VKAPI_REQUEST_HPP
@@ -20,10 +20,10 @@ namespace vk
 namespace base
 {
 
-constexpr long APPLY_CURLOPT = 1L;
-constexpr long NO_APPLY_CURLOPT = 0L;
-constexpr long MAXREGIDS = 50L;
-constexpr const char* USERAGENT = "VKAPI Client";
+_VKAPI_UNUSED_FOR_ANALYZER _VKAPI_CONSTEXPR long APPLY_CURLOPT = 1L;
+_VKAPI_CONSTEXPR long NO_APPLY_CURLOPT = 0L;
+_VKAPI_CONSTEXPR long MAXREGIDS = 50L;
+_VKAPI_CONSTEXPR const char* USERAGENT = "VKAPI Client";
 
 /**
  * @brief The class for working with request.
diff --git a/include/Types.hpp b/include/Types.hpp
new file mode 100644
index 0000000..7020e0b
--- /dev/null
+++ b/include/Types.hpp
@@ -0,0 +1,43 @@
+/**
+ * Contains defined types.
+ * @file Types.hpp
+ * @author qucals
+ * @version 0.0.8 1/09/21
+ */
+
+#ifndef VKAPI_TYPES_HPP
+#define VKAPI_TYPES_HPP
+
+#include "Defines.hpp"
+
+#ifndef __CPLUSPLUS_OVER_11
+typedef signed char        int8_t;
+typedef short              int16_t;
+typedef int                int32_t;
+typedef long long          int64_t;
+typedef unsigned char      uint8_t;
+typedef unsigned short     uint16_t;
+typedef unsigned int       uint32_t;
+typedef unsigned long long uint64_t;
+#endif // __CPLUSPLUS_OVER_11
+
+#include "nlohmann/json.hpp" // nlohmann::json
+
+namespace vk
+{
+
+namespace base
+{
+
+typedef long long int IdType;
+typedef unsigned long long UIdType;
+typedef bool IndicatorType;
+
+typedef nlohmann::json JsonType;
+
+
+} // namespace base
+
+} // namespace vk
+
+#endif //VKAPI_TYPES_HPP
diff --git a/include/UserBase.hpp b/include/UserBase.hpp
index 188fd20..66af3bd 100644
--- a/include/UserBase.hpp
+++ b/include/UserBase.hpp
@@ -2,7 +2,7 @@
  * Describes the class for working with VK account.
  * @file UserBase.hpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
 #ifndef VKAPI_USERBASE_HPP
@@ -484,7 +484,6 @@ class UserBase : public ClientBase
      *
      * @retval a string of this method in URL format.
      */
-    _VKAPI_COMPLEXITY_FUNCTION
     _VKAPI_STATIC std::string MethodToString(METHODS method);
 
     /**
diff --git a/src/BotBase.cpp b/src/BotBase.cpp
index f3cd4f6..ab93c9d 100644
--- a/src/BotBase.cpp
+++ b/src/BotBase.cpp
@@ -2,7 +2,7 @@
  * Contains the class for working with vkbot.
  * @file BotBase.cpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
 #include "BotBase.hpp"
@@ -39,8 +39,7 @@ bool BotBase::Auth(const std::string& accessToken)
     JsonType response = JsonType::parse(Request::Send(url, ConvertParametersDataToURL(parametersData)));
 
     if (response.find("error") != response.end()) {
-        throw ex::RequestError();
-        // TODO (#12): Add error handling when BotBase::Auth failed
+        throw ex::AuthFailed();
     } else {
         JsonType answerDataStr = response["response"];
 
@@ -74,10 +73,9 @@ BotBase::Event BotBase::WaitForEvent()
     JsonType updates = response.at("updates")[0];
     std::string eventStr = updates.at("type").get<std::string>();
 
-    return Event(GetTypeEvent(eventStr), updates);
+    return Event(GetTypeEvent(eventStr), updates); // NOLINT(modernize-return-braced-init-list)
 }
 
-_VKAPI_COMPLEXITY_FUNCTION 
 std::string BotBase::MethodToString(const METHODS method)
 {
     switch (method) {
@@ -247,7 +245,6 @@ JsonType BotBase::CheckValidationParameters(const JsonType& parametersData)
     return cParametersData;
 }
 
-_VKAPI_COMPLEXITY_FUNCTION
 BotBase::EVENTS BotBase::GetTypeEvent(const std::string& typeEvent)
 {
     if (typeEvent == "message_new") {
diff --git a/src/ClientBase.cpp b/src/ClientBase.cpp
index 626f05f..3eb0b27 100644
--- a/src/ClientBase.cpp
+++ b/src/ClientBase.cpp
@@ -2,7 +2,7 @@
  * Contains general objects for working with VK API.
  * @file ClientBase.hpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
 #include "ClientBase.hpp"
@@ -72,15 +72,19 @@ uint32_t ClientBase::GetRandomId()
 
 VK_REQUEST_ERROR_TYPES ClientBase::GetRequestErrorType(const std::string& errorStr)
 {
-    using VK_ERROR = VK_REQUEST_ERROR_TYPES;
-
-    // TODO (#13): Add all VK_ERRORS
     if (errorStr == VKAPI_INVALID_REQUEST) {
-        return VK_ERROR::INVALID_REQUEST;
+        return VK_REQUEST_ERROR_TYPES::INVALID_REQUEST;
     } else if (errorStr == VKAPI_NEED_CAPTCHA) {
-        return VK_ERROR::NEED_CAPTCHA;
+        return VK_REQUEST_ERROR_TYPES::NEED_CAPTCHA;
     } else {
-        return VK_ERROR::UNKNOWN_ERROR;
+        try {
+            VK_REQUEST_ERROR_TYPES __e = static_cast<VK_REQUEST_ERROR_TYPES>(
+                std::stoi(errorStr));
+            return __e;
+        } catch (std::exception& ex) {
+            _VKAPI_DEBUG_STDCERR(ex.what());
+        }
+        return VK_REQUEST_ERROR_TYPES::UNKNOWN_ERROR;
     }
 }
 
diff --git a/src/UserBase.cpp b/src/UserBase.cpp
index feb120d..37657ed 100644
--- a/src/UserBase.cpp
+++ b/src/UserBase.cpp
@@ -2,7 +2,7 @@
  * Describes the class for working with VK account.
  * @file UserBase.hpp
  * @author qucals
- * @version 0.0.7 24/08/21
+ * @version 0.0.8 24/08/21
  */
 
 #include "UserBase.hpp"
@@ -70,9 +70,7 @@ bool UserBase::Auth(std::string& login, std::string& password)
                 std::cin >> captchaKey;
 
                 parametersData.push_back({ "captcha_key", captchaKey });
-                std::string answer = Request::Send(VKAPI_AUTH_URL, ConvertParametersDataToURL(parametersData));
-
-                // TODO (#11): Add further processing
+                response = Request::Send(VKAPI_AUTH_URL, ConvertParametersDataToURL(parametersData));
             }
 
             VALIDATION_TYPES validationType = GetValidationType(response.at("validation_type"));
@@ -218,7 +216,6 @@ JsonType UserBase::SendRequest(const std::string& method, const JsonType& parame
     return response;
 }
 
-_VKAPI_COMPLEXITY_FUNCTION
 std::string UserBase::MethodToString(METHODS method)
 {
     switch (method) {
diff --git a/submodules/install.cmake b/submodules/install.cmake
new file mode 100644
index 0000000..433b376
--- /dev/null
+++ b/submodules/install.cmake
@@ -0,0 +1,26 @@
+if((NOT NLOHMANN_JSON_INCLUDE_DIR) OR (NOT EXISTS ${NLOHMANN_JSON_INCLUDE_DIR}))    
+    message("Unable to find nlohmann/json, cloning...")
+
+    execute_process(COMMAND git submodule update --init -- submodules/json
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
+
+    set(NLOHMANN_JSON_SOURCE_DIR
+    ${CMAKE_CURRENT_SOURCE_DIR}/submodules/json/
+    CACHE PATH "nlohmann/json include directory")
+
+    install(FILES ${NLOHMANN_JSON_SOURCE_DIR}/single_include/nlohmann/json.hpp DESTINATION ${CMAKE_INSTALL_BINDIR}/include/vkapi/nlohmann)
+
+    # Setup a target
+    add_library(nlohmann_json INTERFACE)
+    target_include_directories(nlohmann_json INTERFACE
+                               $<BUILD_INTERFACE:${NLOHMANN_JSON_INCLUDE_DIR}>
+                               $<INSTALL_INTERFACE:include>)
+
+    install(TARGETS nlohmann_json EXPORT nlohmann_json DESTINATION ${CMAKE_INSTALL_BINDIR}/include/vkapi/nlohmann)
+    install(
+        EXPORT nlohmann_json 
+        FILE nlohmann_jsonTargets.cmake 
+        # NAMESPACE nlohmann_json::
+        DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/
+    )
+endif()
\ No newline at end of file
diff --git a/submodules/json b/submodules/json
new file mode 160000
index 0000000..1fd2213
--- /dev/null
+++ b/submodules/json
@@ -0,0 +1 @@
+Subproject commit 1fd2213fd206d12a818cd5c60dd0138445534133